Repeated measures are required to monitor and map trajectories of mental health symptoms that are sensitive to the changing distal and proximal stressors throughout the coronavirus (COVID-19) pandemic. Understanding symptoms in young children is particularly important given the short- and long-term implications of early-onset internalizing symptoms. This study utilized an intensive longitudinal approach to assess the course and environmental correlates of anxiety and depression symptoms in 133 children, ages 4–11 (Mage = 7.35, SD = 1.03), in the United States during the COVID-19 pandemic. Caregivers completed 48 repeated assessments from April 7, 2020, to June 15, 2021, on child and caregiver mental health symptoms, family functioning, and COVID-19-related environmental changes. Results from a series of multilevel growth models demonstrate that child depression symptoms were highest following initial stay-at-home orders (April 2020) and linearly decreased over time, while child anxiety symptoms were variable over the 15-month period. Caregiver depression symptoms and family conflict significantly predicted levels of child depression symptoms. In contrast, caregiver depression symptoms, caregiver anxiety symptoms, and time spent home quarantining significantly predicted levels of child anxiety symptoms. Results suggest that depression and anxiety symptoms in young children may have unique trajectories over the course of the coronavirus pandemic and highlight symptom-specific risk factors for each symptom.